Calorimetric examination of hip pseudo-capsule after secondary hip surgeries

During revision hip surgeries, a soft pseudo-capsule is formed around the artificial joint. The roles of the pseudo-capsule are to protect and to stabilize the joint. Based on intraoperative observation, we have found that different types of pseudo-capsules have different thickness and elasticity, compared to the primary joint capsule. The purpose of the study was to evaluate and identify the different types of pseudo-capsules, based on thermal characteristics and histological examinations. The pseudo-capsule samples were collected during aseptic hip revision (n = 3), septic hip revision (n = 2) and during revision surgery after antibiotic-impregnated spacer implantation (n = 3). The thermal characteristics (maximal denaturation temperature, Tm, and calorimetric enthalpy change, ΔHcal) were determined from the measurements made by SETARAM Micro DSC-II calorimeter between 37° and 90°C with 0.3 K min−1 heating rate. The denaturation scans of different pseudo-capsule samples have clearly demonstrated specific, representative changes, comparing samples with aseptic and septic origins. These changes were confirmed by histological evaluations; therefore, DSC could be a useful tool in the evaluation of hip pseudo-capsules with different origins, providing further help in the differential diagnostics of septic conditions.